The photo shows multiple layers of nacre. It looks similar to a photos I've seen on those "pearl party" pages as a sort of "proof" the pearls are akoya. They think they've found a bead inside the pearl.
What they don't understand is that pearls can be peeled like onions. That "bead" is just where one layer of nacre separated from another. Real akoya have a very thin layer over a large bead.